58 



INTENSITY OF SUN'S HEAT AND LIGHT 



Duration of Civil Twilight, Morning or Evening. 



1853. 



Lat. 0°. 



Lat, 10°. 



Lat. 20°. 



Lat. 30°. 



Lat. 40°. 



Lat. 50°. 



Lat. 60°. 



Lat. 70°. 



Lat. 80°. 



Lat. 90°. 





m. 



m. 



m. 



m. 



m. 



m. 



h. m. 



li. m. 



h. m. 



h. m. 



January 



32 



33 



34 



37 



43 



57 



1 16 



3 2P 



00 



00 



February 



31 



31 



32 



35 



40 



49 



1 15 



1 40 



4 01 a 



00 



March 



30 



3D 



32 



35 



39 



50 



1 03 



1 29 



3 04 



12 00 3 



April 



30 



31 



33 



36 



41 



50 



1 08 



2 09 



00 



00 



May 



32 



33 



34 



42 



45 



58 



1 37 



1 10' 



00 



00 



June 



33 



34 



36 



40 



48 



64 



2 46' 



00 



00 



00 



July 



32 



33 



35 



39 



46 



61 



2 03 



, 00 



00 



00 



August 



31 



32 



33 



36 



42 



52 



1 15 



3 07 1 



00 



00 



September 



30 



31 



32 



35 



40 



47 



1 02 



1 35 



4 42 1 



00 



October 



30 



31 



32 



35 



40 



47 



1 01 



1 31 



3 26 



12 00 3 



November 



31 



32 



34 



37 



42 



51 



1 10 



2 16 



00 



00 



December 



33 



33 



35 



38 



44 



60 



1 22 



2 42 3 



00 



00 



Duration of Astronomical Twilight, Morning or Evening. 



1853. 



Lat. 0°. 



Lat. 10°. 



Lat. 20°. 



Lat. 30°. 



Lat. 40°. 



Lat. 50°. 



Lat. 60°. 



Lat. 70°. 



Lat. 80°. 



Lat. 90°. 





h. m. 



b. m. 



h. m. 



b. m. 



h. m. 



h. m. 



h. m. 



h. m. 



h. m. 



h. m. 



January 



1 13 



1 13 



1 17 



1 24 



1 39 



1 56 



2 38 



5 29 3 



4 35 3 



00 



February 



1 10 



1 10 



1 14 



1 20 



1 30 



1 43 



2 20 



3 32 



7 49= 



12 00 3 



March 



1 08 



1 09 



1 12 



1 19 



1 30 



1 48 



2 21 



3 44 



6 29' 



12 00 s 



April 



1 09 



1 11 



1 15 



1 24 



1 36 



2 01 



3 06 



4 OP 



00 



00 



May 



1 12 



1 14 



1 19 



1 29 



1 48 



2 37 



3 33 l 



1 10 1 



00 



00 



June 



1 14 



1 17 



1 23 



1 35 



1 59 



3 56 1 



2 46' 



00 



00 



00 



July 



1 13 



1 16 



1 21 



1 32 



1 54 



2 59 



3 09 l 



00 



00 



00 



August 



1 10 



1 12 



1 16 



1 25 



1 40 



2 11 



4 18 1 



3 07 1 



00 



00 



September 



1 08 



1 09 



1 13 



1 18 



1 31 



1 51 



2 30 



5 23 1 



4 42' 



00- 



October 



1 09 



1 10 



1 13 



1 19 



1 29 



1 47 



2 18 



3 25 



7 48 



12 00 3 



November 



1 12 



1 12 



1 15 



1 22 



1 33 



1 52 



2 29 



4 14 



5 43 3 



00 



December 



1 14 



1 15 



1 18 



1 25 



1 37 



2 00 



2 47 



5 03 3 



3 S3 3 



00 



1 Twilight through the whole night. 



Note. — Astronomical Twilight includes the duration of Civil Twilight. 



3 Twilight without clay. 



PUBLISHED BY THE SMITHSONIAN INSTITUTION, 

 WASHINGTON, D. C, 



November, 1856. 



